Photovoltaic Modules: Collaboration with Construct PV, Part 1

This article is the first of two posts on the Construct PV project. The project aims to improve photovoltaic (PV) modules through architectural research with a number of international science and industry partners. The research has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 295981. By applying market research in combination with technical and design research, the goal of Construct PV is to convert the standard industrial PV module into a product that offers greater design flexibility to meet requirements of different countries within the European Union.

An additional aim of the research is to create a design catalogue with both aesthetic and cost-effective choices for the implementation of PV modules in the building envelope. A focus area for the project lies in the opaque sections of the building facade and roof, wherein design possibilities can allow for different layering choices in design, colour and finishing. A further aim is to bring these possibilities to the European market, together with our partners in the PV manufacturing industry.

The Construct PV research was structured and organised together with the partners in the Construct PV consortium to determine which architectural effects could be achieved within the technical capabilities of PV module layering. The Construct PV research started from a basic understanding of the existing possibilities of working with PV and integrating it into the building envelope. This ranged from research on the cellular level to designing the placement of cells within the PV module, to integrating PV modules into the facade envelope, and finally at the largest scale to test PV capability on an urban planning level. Within the different architectural scales, design parameters for the Construct PV research were identified together with the research partners and linked to various technical options outlining different design possibilities. Afterwards, a classification of the available design parameters was made to compile a catalogue of options. These options lead to a variety of design outcomes which can be combined into the design of PV modules and integrated into the built environment.

With the first outcome of the design research, the end goal was to build physical examples of the research outcomes to test assumptions in the form of small-scale mock-ups. By building physical representations of the design research, the modules and general quality of the facade could thereby be evaluated before constructing the main project outcome: a large-scale roof and facade.

Based on the experiences and conclusions noted from the small-scale mock-up, the main goal of the research in 2016 focused on the retrofitting of the office facade of the Zueblin Z3 Building in Stuttgart, Germany, and a roof installation atop the university building at the NTUA campus in Athens, Greece.

The range of options discovered for PV design is largely informed by the way production lines are currently organised. In the production of glass-glass PV modules, for example, a fixed number of manufacturing steps are involved in manufacturing the end product on a production line. Apart from traditional steps such as connecting cells, encapsulation and final assembly, other layers of architectural finishing can be considered and introduced in prefabricated elements such as the glass panels. The following layers can act as parameters to enhance the end design:

For the Construct PV project, we are most interested in the back panel colouring and glass finishing (colour and frit). The cell design is based on a more conventional dense coverage of cells in an orthogonal grid, to retain as much of the electrical output as possible.

A clear requirement in the development of PV modules is the factor of cost. The balance of applying a range of designs and materials becomes a question of finding a balance between cost and aesthetic effect.

For example, designs with adapted cell placement might offer possibilities in terms of patterns or transparency. However, it must be taken into account that any loss of coverage in cell surface has a negative effect on electricity production in relation to the standard module. This can have considerable impact on the overall cost and significantly impact the economic value of the PV module. Such a design choice needs to be carefully considered in relation to the desired aesthetic effect. Mass customisation could still be considered, but direct competition with low cost industrial modules may not be interesting because of the high standards required to maintain sufficient facade appearances.

Considering the balance between cost and effect, variation and modularisation play an important role in maintaining the balance between the aesthetics of variation and the economics of repetition. The image below shows patterns that are based on a rationalised organisation of different layers (cells, colours and frit or silk screen printing). By using maximum coverage of PV cells, a large detrimental effect to the energy production can largely be avoided.

The next Construct PV post focuses on the various small and large-scale mock-ups in production for the Construct PV research project. These mock-ups explore the integration of PV on the roof for large-scale installation and production, in addition to testing the compatibility of PV with various facade types.